Chapter 5 AP Biology

Why do phospholipids spontaneously form bilayer structures, while oils form small droplets?

Oils do not have the polar head group that phospholipids have.

Which statement about membrane proteins is true?

Peripheral membrane proteins may be associated with the phospholipid head groups.

What is allosteric regulation?

a proteins shape is changed to turn a protein/boding site off/on

A cell will use carrier proteins to transport a compound across its cell membrane because the compound is

a reactant in an essential metabolic reaction that runs at a rate greater than the rate of simple diffusion. concept: A particle may bind to a carrier protein to move it along faster in simple diffusion.

The process of diffusion leads to

achieving equilibrium of solute and solvent molecules in a solution. Concept: There are two ways to go through a membrane: Active Transport which uses and input of metabolic energy for the substance to move against the gradient and Passive trasnport where the particle moves with the gradient and requires no energy. Simple diffusion is general movement from high to low concentration and facilitated diffusion is through channel proteins or it is aided by carrier proteins (pores in membranes).

In the signal cascade triggered by epinephrine in liver cells, glycogen phosphorylase is

activated and releases glucose.

If a cell is bathed in an extracellular solution high in calcium ions, it would use _______ to maintain a normal, low intracellular concentration of calcium ions.

active transport against the concentration gradient of Ca2+

Osmosis, the movement of water though specialized membrane channels, is a specific form of

diffusion

What is Phagocytosis and what is it part of

it is part of endocytosis. It lets the cell engulf molecule and digests molecule after binding to lysosome.

What are G proteins

linked receptor 2 imbedded and 1 peripheral protein

The cell membrane contains carbohydrates, which can serve as recognition sites for other molecules. The carbohydrates may be covalently bonded to

lipids and proteins.

The main components in biological membranes are

lipids, proteins, and carbohydrates.

Osmosis involves movement of water across membranes in the direction from a _______ to a(n) _______.

low concentration of solutes; high concentration of solutes

What is endocytosis

the membrane vaginates or folds around the molecule.

Characteristics of three different vesicles isolated from a cell are summarized in the table above. Which vesicle(s) would you expect to contain receptor proteins lining their interior walls?

B and C

Which statement about receptors and enzymes is true?

Both receptors and enzymes may be integral membrane proteins.

How does facilitated diffusion by channel proteins differ from facilitated diffusion by carrier proteins?

Channel proteins form a pore through the membrane to allow substances to pass, whereas carrier proteins bind to and change conformation as they transport substances through the membrane.

Suppose a new signal transduction pathway has been discovered that may involve either an ion channel receptor or a G protein-linked receptor. Which procedure could provide information that could help distinguish between these two possibilities?

Check to see whether signal transduction is correlated with cell uptake of a small polar substance labeled with a radioisotope.

Which is a function of the proteins lining the extracellular surfaces of coated pits involved in receptor-mediated endocytosis?

Forming the receptors that bind a specific molecule

What are the different types of solutions and which different cells like which ones

Hypertonic: Solution is high solute and low water Isotonic: Solution is the same concentration of solute and water Hypotonic: Solution has low solute concentration and high water concentration. Cells don't like hypertonic solutions. Animal cells want isotonic and Plants want Hypnotic so they can get water and become stronger with turgor pressure

What are two benefits of having a cascade of cellular events during signal transduction?

Increased amplification of the signal and increased distribution of the signal

Cell membranes of root cells from broccoli plants were analyzed following 15-day exposure to no-salt or added-salt conditions. The results are summarized in the table above. The plants grew normally under both control and added-salt conditions. What do the results imply about cell membrane composition in response to salt stress?

It shifts toward greater unsaturated fatty acid content in order to withstand salt stress.

How could you distinguish between a signal transduction pathway that leads to an alteration in gene expression and a pathway that leads to an alteration in enzyme activity?

Look at the timing of the cellular response to signal molecules to determine whether the response is very fast or relatively slow.

How do macromolecules fit through a membrane

Macromeolecules are to large for a membrane protein. they cross with vesicles using using endocytosis and exocytosis which is used for secretion and excretion.

When a severely dehydrated patient is brought to the hospital, an intravenous drip of saline is started immediately. Sterile deionized water is not used because

When a severely dehydrated patient is brought to the hospital, an intravenous drip of saline is started immediately. Sterile deionized water is not used because

Which of the following statements about diffusion is false?

Which of the following statements about diffusion is false?

There are two basic types of active transport. A main difference between them is that only one uses

a concentration gradient established by a previous reaction to drive transport.

A protein that forms an ion channel in a membrane is most likely to be

a transmembrane protein. Concept: There are two kinds of proteins in a membrane. One is peripheral which is on the surface and is non polar. The integral is impeded in the membrane and can also be called a transmembrane protein where inside is hydrophobic and outside is hydrophilic.

Second messengers

are found in the cytoplasm.

A signal made by an animal cell that affects that same cell is a(n) _______ and a signal that is made by an animal cell and that diffuses to and affects a nearby cell is a(n) _______.

autocrine signal; paracrine signal

Suppose the concentration of epinephrine in the bloodstream of an animal drops. The cyclic AMP concentration in liver cells would be expected to _______ because _______ activity would _______.

decrease; adenylyl cyclase; decrease

Phosphodiesterase is the enzyme that catalyzes the degradation of cAMP in cells. Phosphodiesterase inhibitors have been synthesized and used as drugs in the treatment of several human diseases and disorders. Based on the role of cAMP in the signal transduction pathway shown above, you would expect these drugs to

enhance the effects of epinephrine to shift the production of glucose to increased amounts.

Cells secrete materials to the exterior environment through the process of

exocytosis.

In biological membranes the lipid bilayer contains phospholipids, each with a head and two fatty acid tails. They are arranged so that the

fatty acid tails point toward each other.

Active transport moves molecules

in a direction opposite to the one in which diffusion would move them.

In the signal cascade triggered by epinephrine within liver cells, glycogen synthase is

inactivated and does not produce glycogen.

Epinephrine stimulates a G protein-mediated cascade within liver cells, resulting in phosphorylation of two enzymes: glycogen synthase and glycogen phosphorylase. This results in _______ glucose moving into the blood and _______ glycogen storage in liver cells.

increased; decreased

Based on the figure above, cortisol acts as a signal and binds to its receptor, which is a(n) _______ receptor.

internal

Chemical signal transduction pathways

involve binding of the signal molecule to receptors.

The phosphorylation of proteins by ATP

is catalyzed by enzymes known as "protein kinases."

What is a secondary Messenger

it carries a message to other places. It amplifies signal. A common one is cyclic AMP (cAMP) which activates protein kinase and which can inhibit or activate other things.

What are membrane receptors

large, polar, cannot diffuse. A chemical ligand fits into the 3d structure of protein to turn it off/on,, but this has to be reversible for homeostasis. Inhibitors or antagonists bind in place of normal ligand. An example of a receptor that needs a ligand is an ion channel receptor

A molecule that binds to the particular three-dimensional structure of a receptor site is known as a(n)

ligand.

The main difference between osmosis and diffusion is that

osmosis refers specifically to the movement of water across a membrane, whereas diffusion refers to the movement of any particles.

A researcher places a cell in a solution containing solutes A and B. Given the data shown, you can predict that there will be net movement of solute A _______ the cell and net movement of _______ the cell.

out of; water out of

What is Pinocytosis and what is it part of

part of endocytosis. This lets water in and particles come in with it.

White blood cells can defend the body against invaders through

phagocytosis.

What are the 3 steps in cell signaling

reception, transduction (carrying signal) and response

Mice having a genetic mutation that prevents the production of a protein called megalin were compared to healthy mice that produce normal amounts of megalin. Using the data shown in the table, it is likely that megalin is a(n)

receptor protein in kidney cells that binds and takes up vitamin B12 in receptor-mediated endocytosis to prevent its excretion in urine.

An important difference between phagocytosis and receptor-mediated endocytosis is that

receptor-mediated endocytosis is more specific.

Mammalian cells acquire specific macromolecules from their environment by the process of

receptor-mediated endocytosis.

If hydrolysis of ATP is temporarily blocked, the sodium-potassium pump will

remain unphosphorylated and unable to move Na+ out of the cell.

The sodium-potassium pump (or Na+-K+ pump)

results in the formation of an Na+ concentration gradient across the cell membrane.

Receptor-mediated endocytosis

results in the formation of clathrin-coated vesicles.

All of the following are ways that cells change in response to signals except

signal activation.

In facilitated diffusion,

specific integral membrane proteins mediate transport.

What is Receptor endocytosis

specific molecules body to these and are brought in. Nucleus controls where and how much are there to regulate where and how much molecules come in. they also play a role in cell signaling

If a suspension of red blood cells in an isotonic NaCl solution was suddenly diluted with pure water by a factor of 10, the cells would

swell and lyse (burst).

What does higher substance concentration on one side mean.

that one side has potential energy

If aquaporins are injected into the membranes of a cell that does not normally contain them,

the membranes will become more permeable to water. concept: Auquaporins are where large amounts of water can flow through.

Osmosis is

the movement of water across selectively permeable membranes.

All of the following affect the rate of diffusion of a substance except

the presence of other solutes in the solution. concept: speeding up diffusion includes smaller molecules, more heat, and more concentration.

What is turgor pressure?

the water pressure inside the vacuole of the plant cell in response to the force of water within the cell

What are the 3 ways cells respond to a transmission

they open ion chains or (nervous) carry electrical signals to open them. They alter the gene expression they alter the enzyme activities. Some cells react differently because different transduction pathways.

Hormones are chemical signals that

travel through circulatory systems.

A universal feature of receptors is that they

undergo structural (shape) changes when the signal molecule is bound.

All of the following may be involved in facilitated diffusion except

ATP, which is used as an energy source.

In the figure above, part of the signal transduction mechanism common to G protein-linked receptors is shown. Of the steps in this pathway, select the step that will occur next.

Activated G protein subunit binds to effector protein.

Which type of cellular response represents a long-term response to an external signal?

Activation of a gene expressing an enzyme

How does active transport work with ATP

Active transport uses the ATP to remove/add molecules to maintain homeostasis through specific carrier proteins. Primary Active Transport involves direct hydrolysis for ATP Secondary Active Transport is when ATP makes gradient to move stuff (uses potential energy as kinetic). This also leads to passive diffusion which is other molecules switching places with those leaving/coming in

In the fluid mosaic model, some proteins are able to move freely within the membrane, while others, such as proteins in a muscle cell membrane, are anchored or restricted in their movement. What is the best explanation for a cell's restriction of some proteins to a specific region of the cell membrane?

A protein's function may depend on its presence in a specific location.

What is osmosis

Diffusion of water. It moves down a concentration gradient. Osmotic Pressure is the treasure that needs to be applied to prevent osmosis.

The fluid mosaic model of a biological membrane suggests that the membrane is made up of discrete units that can move freely. Which components determine the fluidity of the membrane?

Phospholipids and cholesterol Concept: The lipids in the membrane are phospholipids with 2 regions: Hydrophillic (charged heads) and hydrophobic (nonpolar tails). A bilayer forms when these associate. Cholesterol is used to maintain membrane fluidity and it happens when hydroxyl groups interact with heads

If a person becomes dehydrated and needs to acquire dissolved solutes rapidly, which cellular process would likely be accelerated?

Pinocytosis

Which of the following statements about receptors is true?

Receptors are specific to the signal ligand.

Acetylcholine is a small molecule involved in the transmission of nerve impulses from one neuron to another. Inside a neuron, acetylcholine moves from the cytoplasm into secretory vesicles, which then move to the cell membrane for release of acetylcholine into the extracellular medium. While investigating this process, a biologist observed that a hydrogen ion gradient was associated with acetylcholine secretory vesicles. In a series of experiments, the biologist tested both the formation of this hydrogen ion gradient and the uptake of acetylcholine into vesicles under various conditions. The conditions used and their corresponding results are summarized in the table above. Which acetylcholine transport mechanism is consistent with these data?

Secondary active transport

What are internal Receptors

Small, non polar messegas that can diffuse across the membrane to the outside

What type of molecules uses simple diffusion and what type of molecules use facilitated diffusion

Small, non polar, lipid soluble molecules use simple diffusion Large, polar molecules use facilitated diffusion.

The figure shows the activity of the acetylcholine receptor. Based on the information shown, which statement about the acetylcholine receptor is true?

Sodium ions diffuse into the cell only when acetylcholine binds to the membrane receptor.

Cytoskeletal proteins are important for maintaining the structure of the cell, but some of their components also have other functions affecting the cell membrane. If cytoskeletal proteins were temporarily disrupted, what might take place in the cell membrane?

Some attached membrane proteins would detach and move freely.

The fatty acid composition of the intestinal cell membranes from three different fish species were analyzed. One species lives in Antarctic Ocean waters, another in the northern Atlantic, and the third in the Mediterranean Sea. Use the data to match each species with its native waters.

Species 1: northern Atlantic; Species 2: Mediterranean; Species 3: Antarctic

What is cell signaling and what are the 4 ways

Stimuli binds and cell responds Autocrine: effect same cells that release them Paracrine: diffuse to nearby cells and effect them Juxtacrine: direct contact between signaler and responding cell Endocrine:hormones spread everywhere

A cell requires movement of Substances 1, 2, and 3 from the extracellular medium into the cell to sustain life functions. Based on the information given in the table, which mechanisms would enable the cell to transport each substance, while maximizing conservation of its energy resources?

Substance 1: active transport; substance 2: facilitated diffusion; substance 3: simple diffusion

Cyclic AMP is synthesized and degraded by two different enzymes in cells. Explain which of these enzymes is important in the regulation of signal transduction pathways that rely on cAMP as a second messenger, and why.

The activities of both enzymes are important because together they determine the level of cAMP in the cell, which in turn determines the degree of signal transduction.

Which occurs during both endocytosis and exocytosis?

The cell membrane undergoes compositional change.

Enzyme Z activity was measured in cells as a function of the concentration of a hormone present in the extracellular medium. These measurements are summarized in the top row of the table above. A second batch of cells was treated with a protease, which is an enzyme that degrades proteins on the exterior of the cell. Protease-treated cells were then tested for activity in the presence of various concentrations of hormone as shown in the second row of the table. These data can be used to distinguish between several different signal transduction models that have been proposed for this system. Which signal transduction model fits these data?

The hormone binds to a protein receptor on the cell surface that undergoes a conformational change that leads to inhibition of enzyme Z.

In the figure shown, what can be concluded about the signal transduction pathway that is initiated when insulin binds to its receptor?

The intracellular domains of the receptor become phosphorylated before they initiate a response in the cell.

Suppose a shallow pan is filled with water and a drop of red ink is placed in one end of the pan and a drop of green ink is placed in the other end. Which condition can be predicted to exist once the system has reached equilibrium?

The red and green inks will be uniformly distributed throughout the pan.

Which statement is true about signal molecules?

The same signal molecule can target different cells in different ways.

What are protein kinase receptors

They add phosphate groups to another molecule (phosphorylation)

Receptors bind noncovalently to their ligands according to the law of mass action. This means that

binding is reversible and dependent on ligand concentration.

The figure above shows the signal transduction pathway initiated by the binding of an odorant molecule to an olfactory receptor of an olfactory neuron in the human nose. Information will be sent to the brain because of changes in ion concentrations within the neuron. What specific event is most directly responsible for the change in intracellular ion concentrations?

cAMP binding to its gated channel

Which statement about a signal cascade is true?

cAMP is referred to as a "second messenger."

Channel proteins

can allow movement of substances either into or out of the cell. concept: Channel proteins provide a hole in the membrane and use facilitated diffusion and/or simple diffusion. Ion Channels are when specific ions flow through. Channels can be locked or unlocked (gated channels). In Nervous system, the gate is unlocked with a certain voltage. In everything else, the gate is unlocked with a ligand which is the chemical stimulus. The protein Chanel on the outside is hydrophobic and the inside is hydrophilic.

Cell-to-cell adhesion often occurs through the interactions of

carbohydrates Concept: There are 3 types of Carbohydrates on the outside of a cell. A Glycolipid which is covalently bonded to a lipid. A Glycoprotein is one or more oligosaccharides covalently bonded to a protein and a Proteoglycan is a protein with more and longer carbohydrates bonded to it. Proteins and Carbs help attach and cancer happens when this adhesion breaks

In addition to the lipid bilayer and proteins, membranes may contain _______ in the form of _______ and _______.

carbohydrates; glycoproteins; glycolipids